TITLE: GCN CIRCULAR NUMBER: 45254 SUBJECT: EP 260729a: Ondrejov D50 optical detection supports stellar flare origin DATE: 26/07/29 22:52:45 GMT FROM: Martin Jelinek at Astro.Inst-AVCR,Ondrejov <martin.jelinek@asu.cas.cz> M. Jelinek, J. Strobl, F. Novotny and R. Hudec (ASU CAS Ondrejov) report: We observed the position of the Einstein Probe transient EP260729a (Zhou et al., GCN 45253) with the D50 telescope of the Astronomical Institute Ondrejov, near Prague, Czech Republic, obtaining 19x120s r'-band exposures starting at 21:13 UT on 2026 July 29 (~4.1 h after the WXT trigger). We find no uncatalogued object in the error circle down to r>21.5 (3-sigma) in the combined image. The M4.0V high proper motion star RX J2350.0+2659 (ATLAS-RefCat2 r=13.876; Zhou et al., GCN 45253) is bright and well detected in single exposures. It appears elevated in brightness at the start of our sequence, fading over ~40 minutes. A linear fit gives an initial excess of ~0.14 mag over its catalogued magnitude, decaying at ~0.1 mag/hour. This fading excess supports the stellar flare origin of EP260729a suggested by the EP team (Zhou et al., GCN 45253). View this GCN Circular online at https://gcn.nasa.gov/circulars/45254. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...